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Isolation And Ammonia-oxidizing Activity Study Of Ammonia-oxidizing Bacteria In Apple Orchard Soils

Posted on:2017-12-20Degree:MasterType:Thesis
Country:ChinaCandidate:P GeFull Text:PDF
GTID:2323330485971694Subject:Microbiology
Abstract/Summary:PDF Full Text Request
Ammonia oxidation, a rate-limiting step of soil nitrification process, plays an important role of soil N element ecosystem which is mainly composed of ammonia oxidizing bacteria (AOB, ammonia-oxidizing bacteria).Up to the present day, most of the molecular biology techniques used to study of soil ammonium oxidation whose distribution characteristics in different environment. While the study of traditional separation of autotrophic and heterotrophic ammonia oxidizing bacteria and their ammonia oxidation characteristics is relatively lacking. Although, Because of the autotrophic ammonia oxidizing bacteria, which is important microbes in the process of soil nitrogen transformation, grow slowly in culture so it is difficult to isolated pure strains.Which hinded the study development of AOB's physiological activity and the nitrogen transformation function.To further understand the different nutrients typs AOB's mechanism of action and the contribution to the ammonia oxidation process in soil ecosystem, this project isolated AOBs from apple orchard soil by silicon culture method and 16SrDNA sequence analysis technology. Therefore, study the nitrification potential of autotrophic and heterotrophic ammonia oxidizing bacteria by research the influence of environmental factors such as the temperature, pH value, attachment on the strains of ammonia oxidation activity.The research results show that the 18 AOB strains with ammonia oxidation activity were isolated from apple orchard, Then the 4 predominant AOB strains was isolated through the primary and secondary screening.The result shows that 4 strains are shot rod and gram-negative.The strain of SY5-4 cell size is about 1.09×0.69?m and SY11-10 is about 1.00 ×0.54?mThe single colony is white and spherical,with even edges and a smooth surface; The strain of D-21 cell size is about 0.5?0.8?m×0.7?1.3?mand F-11 is about 0.7-0.9?m×0.8?1.4?m The single colony is white and spherical,arranged closely with even edges and needle tip-like.Their 16SrDN A gene show that strain S Y5-4 is Ensifer and strain SY11-10 is Sinorhizobium.which are heterotrophic ammonia oxidizing bacteria,the strain D-21 and F-11 are Nitrosospira, which are autotrophic ammonia oxidizing bacteria.By single factor test and contrast test AOB strains obtained the optimal growth conditions were determined as the initial concentration of ammonia nitrogen as 2 g/L.For the 4 strains,the optimum temperature was 28? and the optimum growth pH value is 8.0. Adding CaCO3 as adsorbate ammonia-oxidizing activity of 4 strains was significantly improved. In the above conditions, when cultured 15d,the 4 AOB strains OD600 up to the maximum value.
Keywords/Search Tags:Ammonia oxidizing bacteria(AOB), Ammonia oxidation activity, Orchard soil, Environmental factors
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